Add receiver notified when overlays need to be hidden
Catch IOException if script already ends with "exit"

Also reformatted a few comments around the affected code block
Update .gitignore
Update Gradle wrapper to 2.1
Update Android Gradle plug-in to 0.13.3
Update Gradle build files
Update Android SDK platform to 21
Merge pull request #22 from friederbluemle/update-project

Update Android SDK platform to 21 + Gradle updates